Telephone transmitter and receiver, loud-speaking telephone, and like sound-emitting device



Aug. 4, 1925,

A. P. YOUNG ET Al. N

LOUD SPEAKING TELEIHONE TRANMITTER AND REGEVER,

TELEPHONE, AND LKE SQUNU ENHTTNS: DEVCEI Filed Sept. 150, 1924 FLS. 2

Invenbors: Arthur @.Youncg;

John H. Butcher;

"Their` At,b orrne5.

Patented Aug.. 4, 1925.

siren s'rA'rEs PATENT' OFFICE.

ARTHUR PRIMROSE YOUNG, AF KENILWORTH, AND JOHN HENRY BUTCHFLR, 0F

RUGBY, ENGLAND, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK.

TELEPHONE TRANSMITTER AND RECEIVER, LOUD-SPEAKING TELEPHONE, AND LIKE f SOUND-EMITTING DEVICE.

Application led September -HQ`1924. Serial No. 740,802.

To all. inkom it may concern.'

Be it known that We, ARTHUR PRIMRosE Yonne. and JOHN HENRY BU'roHnn, subjects of the King of Great Britain, residing,

respectively, at Kenilworth and at Rugby,

in 'the county of Warwick, Englanch' have invented certain new and useful Improvements in Tele hone Transmitters and Receivers, Loudpeaking Telephones, and` like Sound-Emitting Devices, of which the following is a specilication.

Our present invention relates to Sound'- transmitting instruments, `such l. .ting telephones or transmltters, and particufrly to an improved arrangement cf mage'aetic circuit for such instruments. i

According the present invention, 1n sound instruments in which a. permanent magnet is located centrally, of a cup-shaped or bowl-shaped `vessel of .magnetic material,

a magnetic path is provided, extending from the magnet to the side of the vessel, to serve as a shunt path for, the flux associated with current in the actuating edil or coils.

The preferred construction comprlses a spider-bracket, washer or disc of a magnetic material adapted to titrourd the magnet and lie in a piane 'at right angles t'o the principal axis thereof. This spider-bracket, was er or disc may be secured tothe side of the vessel leaving a small air gap around the magnet, or secured to thefmagnet leavlng a small air gap between itself and the side of the vesselgor, thirdly, it may be secured both to the magnet and the side of the vessel,

thus providing a shunt path without any air ffii n lli any of the above constructions the actuating coil may bedisposed around the permanent magnet and the magnetic shunt may be arranged between the actuating coil and that pole of the permanent ,magnet which rests upon the base of the vessel. Obviously, in cases in which the coil occupies only a relatively .small length of the magnet,

a number of positions are available betweenthe lower end of the coil and the base of the vessel in which the magnetic shunt may be mounted. Generally speaking, when the magnetic shunt is mounted near the free end or near the base ot'the magnet, a small airgap or equivalent reluctance will be included in the shunt circuit, and, as the magnetic shunt is placed nearer the centre or neutral point of the magnet, the reluctance or airgap will be decreased.

The invention further comprises arrangging an actuating coil on the shunt path in- ,.jtead or directly on the magnet. Two or "more actuating coils may be employed,

each being disposed radially with respect to the magnet upon an armr of the spiderbracket. Preferably similar coils, symmetrically disposed in the same plane around the magnet, are used, and the spider-bracket may consist of only two diametrically-.projecting cores, formed of soft iron laminations or the like, secured to the` magnet on opposite sides thereof and in a.y plane at right angles to the axis of the magnet.

When thempresent invention is. applied to loud speaking telephones or telephone transmitters of great power, the size of the vessel and of the magnet may be increased and/or the number of turns of the actuating coils.

By way of example the accompanying 4drawing shows the invention applied to telephone receivers ofthe watch case type.

Figs. 1, 2 and 3 are cross-sectional views of modifications in which the actuating coil is located upon the central magnet. Figs. 4 and 5 show a modification in which an actuating coil is placed onthe shunt path; Fig. 4 being a section about the line 4-4 in Fig. 5, except that the cap and diaphragm are not shown in Fig. 5.

Like reference numerals are used to designate similar parts, and 11 indicates the cupshaped or bowl-shaped vessel of magnetic material, which may itself form the casing of the instrument, in which case it is` preferably lacquered, bronzed, or treated in some similar manner or it may be placed in al covering of ivorine, wood, or the like. Centrally and axially of the bow 511 is located the permanent banmagnet 'making contact with the bottom of tiievessel. The barmagnet is shown as being circular in section. A. magnetic diaphragm 13 is retained .against the open end of the vessel by means of a cap of insulating material 14 adapted to screw on to the open end of thevessel 11. The shunt path is designated by the reference numeral 15. In Figs. 1, 2 and 3, it may be in the form of a disc or washer, or of a num- 'laA ber of radially-extending arms, and the coil 16 is arranged so as to oci-upy substantially the wholev of the magnet between its free pole and the shunt path. In Figs. 1 and| 3 a small air-gap is includetl in the shunt path, but in F ig. 2 the reluctance path, which is associated with the neutral point of the magnet, is a minimum.

In the arrangement shown in Figs. 4 and the shunt path is formed by two' dief metrically-projecting limbs 151 and 152 secured. to the central magnetV by .means of a clamping-piece 17. Two actuating coils are rovided, each arranged upon one of the imbs of the shunt path. These actuating coils are connected so that when current of given sense is impressed on the coils, like poles are produced at the free ends of the limbs, A small air-gap is left between each limb and the vessel, say, a proximately of .01 inches. The telephone eads 18 may be secured to the terminals 19 mounted upon a piece of insulating material 20.

In the construction shown in Figs. 4 and 5, the path of the flux due to an oscillating current in the coils comprises the limbs 15V and l5',a portion of the central magnet, the

air-gap between the diaphragm and the free end of the magnet, and a portion of the side of the vessel. rEhe oscillating linx therefore travels .along a relatively small portion of the magnet and consequentlv there is less tendency for the magnet to hecome deenergized by the influence in this arrangement han, for instance, in the construction illustrated in Fig. 8. v

With slight modification the invention may he applied to loud-speaking telephones or telephone transmitters of `various types.

lVhat We claim as new and desire to secure by Letters Patent of the UnitedStates, isz- 1. The combination in a sound instrument of a receptacle of magnetic material, a per marient ma et arranged centrally therein and a mem er ofy magnetic material which forms a shunt magnetic pathl between the magnet and the side of the receptacle..l

2. The combination in a sound instru ment of a receptacle of magnetic material, a, permanent magnet arranged centrally of Vthe shunt of the oscillating fluxA therein and a. member of magnetic material-Y iv'nich forms a shunt magnetic path between manent magnet arranged centrally therein' and a member of magnetic material which forms a shunt magnetic path between the magnet and the side of the receptacle. said member extending in a plane at substantially a right angle to the axis of the magnet.

5. The combination in a sound instrument of a receptacle of magnetic material, a permanent4 magnet arranged centrally therein, a member of magnetic material which forms a shunt magnetic. path between the magnet and the side ofthe receptacle and an actuating coil surrounding said member.

G. The combination in a sound instrument of a receptacle of magnetic material, a permanent magnet arranged centrally therein, a pair of .'nembers of magnetic material projccting diametrically from Athe. magnet toward the sides of thev receptacle and. a pair of actuating coils surrounding said members. y A i 7. The combination in a sound instrument ola receptacle of magneticmaterial, "a permarient 'magnet arranged centrally therein, pair of members of magnetic material Ypro jecting di'ametrically from the magnet toward the sides of the receptacle aifl a pair of actuating Ycoils surrounding said members, said members being separated from the side of said receptcle by a short air gap. 4In iwitness whereof, We have hereunto set out. hands this fourth (lay of September 192eA y `asin riuisinosis.Yonne .man nenni* Birreria-n. 

